This is a pilot study to attempt to immunize male and female macaques to an androgen dependent, epididymis specific protein associated with sperm function. The rationale is that immunization of the female, with secretion of antibody into the female reproductive tract, will interfere with fertilization. The DNA associated with expression of EP2 was used as antigen, administered intradermally using a gene gun. Of eight females injected, two demonstrated evidence of antibody formation. Although possible delayed, pregnancy was not inhibited. Future work will be directed to optimization of the vaccination schedule and alteration of the route of DNA administration in order to maximize antibody production prior to reproductive challenge.